The invention relates to a ball screw, comprising a threaded nut with thread channels for rolling bodies, a threaded spindle with thread channels for rolling bodies, and an intermediate bush, which is arranged between the threaded nut and the threaded spindle, wherein the intermediate bush has thread channels, which face the threaded nut and are adapted to the thread channels of the threaded nut, and rolling bodies are guided in theses thread channels, and wherein the intermediate bush has thread channels, which face the threaded spindle and are adapted to its thread channels, and rolling bodies are guided in these thread channels.
The invention also relates to a method for displacing a threaded spindle in a ball screw, in which an intermediate bush is driven with a rotary movement, the intermediate bush being rotatably mounted in a threaded nut by means of rolling bodies and thread channels and the threaded spindle being rotatably mounted in the intermediate bush by means of rolling bodies and thread channels.
Ball screws are used in various applications. Embodiments of ball screws are described, for example, in the book “Kugelgewindetriebe und Linearfuhrüngen” by J. Ackermann, Verlag Moderne Industrie, 1991.
A ball screw with a threaded spindle and a threaded nut, each having thread channels adapted to one another, in which rolling bodies are guided, is known from EP 1 350 988 A1. One or more return channels for returning rolling bodies with a substantially axial return direction are provided, a return element being provided for deflection from a thread channel into a return channel or vice versa.
A mechanism for actuating a vehicle brake with a central threaded spindle is known from DE 197 05 106 A1. The threaded spindle is secured in a stationary housing against rotation and is arranged so as to be axially displaceable toward a brake disc of the vehicle brake and away therefrom. The device comprises a spindle nut surrounding the spindle together with rolling bodies, said spindle nut being coupled at the end face to the rotatable rotor of an electric motor. The spindle nut is surrounded by a further nut and rotatably mounted therein by means of rolling bodies, said further nut being axially held in the stationary housing as the outer nut.
EP 0 151 788 discloses a ball screw with a piston which is arranged so as to be displaceable back and forth inside a body with a torque-transmitting first ball path.